In evolutionary terms, can we say which among bacteria, spiders, fish and chimpanzees have a ‘better body design’ why or why not ?
No, because different designs are the product of evolution and different species have different body design to suit or adapt to their environment.
Choose the one term from the following which includes the other three :
broccoli, wild cabbage, cauliflower, cabbage
Which of the processes, sexual reproduction or asexual reproduction, brings about maximum variations in the offsprings ?
Gregor Mendel’s first law of genetics states “Of a pair of contrasted characters, only one can be represented in a gamete by its internal ‘factor’.
(a) Give the modern name for this ‘factor’.
(b) State where these factors are found in gametes.
Why are the small numbers of surviving tigers a cause of worry from the point of view of genetics ?
Can the wing of butterfly and the wing of a bat be considered homologous organs ? Why or why not ?
What type of plants were used by Mendel for conducting his experiments on inheritance ?
Name two animals having homologous organs and two having analogous organs. Name these organs.
Name the various tools of tracing evolutionary relationships which have been used for studying human evolution.
a) Name the scientist who gave the theory of origin of life on earth. What is this theory ?
(b) How are those species which are now ‘extinct’ studied ?
A study found that children with light-coloured eyes are likely to have parents with light-coloured eyes. On this basis, can we say anything about whether the light eye colour trait is dominant or recessive? Why or why not?
During which stage can the chromosomes be seen clearly? Write the features of the eukaryotic and prokaryotic chromosomes.
Who provided the evidence of DNA as the genetic material? Write the names of the components of the DNA molecule.
Which of the following combinations of sex chromosomes produce a male child : XX or XY ?
Name one reptile in each case where higher incubation temperature leads to the development of : (a) male progeny, (b) female progeny.
Fill in the following blanks with suitable words :Fill in the following blanks with suitable words :
(a) Genes always work in …………………
(b) In pea plants, the gene for dwarfness is………………… whereas that for tallness is…………………
(c) Most people have………………… earlobes but some have………………… earlobes.
(d) A human gamete contains………………… chromosomes whereas a normal body cell has………………… chromosomes in it.
(e) All races of man have………………… blood groups.
(f) The………………… chromosomes for a………………… are XX whereas that for a………………… are XY.
(a) If a normal human cell has 46 chromosomes, how many chromosomes will be there in a human (;) sperm cell, and (ii) zygote ?
(b) What sizes of plants are produced if both parents have genes Tt ?
In a human, how many chromosmes are present in :
(a) a brain cell ?
(b) a sperm in the testes ?
(c) an egg which has just been produced by the ovary ?
(d) a skin cell ?
(e) a fertilised egg ?
(a) Why did Mendel choose pea plants for conducting his experiments on inheritance ?
(b) State Mendel’s second law of inheritance.
(a) What do you understand by the term ‘variation’ ?
(b) Name two human traits which show variation.
Why are human beings who look so different from each other in terms of size, colour and looks said to belong to the same species ?
Does geographical isolation of individuals of a species lead to the formation of a new species ? Provide a suitable explanation for your answer.
Bacteria have a simpler body plan when compared with human beings. Does it mean that human beings are more evolved than bacteria? Provide a suitable explanation.
A man with blood group A marries a woman with blood O and their daughter has blood group O. Is this information enough to tell you which of the traits blood group A or O is dominant ? Why or why not ?
Why are the small numbers of surviving tigers a cause of worry from the point of view of genetics ?
Explain with examples how the following are evidences in favour of evolution in organisms. (i) Homologous organs (ii) Analogous organs (iii) Fossils [Delhi]
How are fossils formed? Describe, in brief, two methods of determining the age of fossils. [All India]
Name five varieties of vegetables which have been produced from ‘wild cabbage’ by the process of artificial selection.
What are fossils ? Giving one example, explain how fossils provide evidence for evolution.
(a) What is meant by a species ? Give two examples of plant species and two of animals.
(b) State the various factors which could lead to the formation of new species.